# dpkg -i /var/cache/apt/archives/pve-firmware_1.0-14_all.deb
(Reading database ... 39867 files and directories currently installed.)
Unpacking pve-firmware (from .../pve-firmware_1.0-14_all.deb) ...
dpkg: error processing /var/cache/apt/archives/pve-firmware_1.0-14_all.deb (--install):
trying to overwrite '/lib/firmware/RTL8192SU/rtl8192sfw.bin', which is also in package firmware-realtek 0.28+squeeze1
dpkg-deb: subprocess paste killed by signal (Broken pipe)
Errors were encountered while processing:
/var/cache/apt/archives/pve-firmware_1.0-14_all.deb
The installation of Debian 6 (amd64) is clean. How to investigate the problem deeper?
Solved by removing package firmware-realtek.